Bio& 242, Human A&P 2 Unit 1/Lecture 5

Transcription

1 Bio& 242, Human A&P 2 Unit 1/Lecture 5 Overview of Energy and Metabolism 1. The food we eat (carbohydrates, lipids, proteins, and nucleic acids) are our only source of energy for doing the biological work of cells. 2. All molecules (nutrient molecules included) have stored (potential) energy in the bonds between their atoms. 3. The energy that runs most biological systems on earth comes from solar energy 4. Plants trap solar energy via the metabolic reactions of photosynthesis by producing these molecules 1

2 Overview of Energy and Metabolism Terms Calorie: basic unit of measurement of energy in biological system. Indicated by a c In human metabolism, Calorie is really a kilocalorie or 1,000 calories. Indicated by a C This calorie C is the amount of energy required to raise the temperature to 1 kg of water 1 degree C. The caloric needs of most organisms is measured as Basal Metabolic Rate (BMR) Overview of Energy and Metabolism Terms BMR is the minimum resting energy expenditures by an awake alert person Average BMR: 70 C/hr or 1680 C/day If we assume that average amounts of carbohydrates, lipids and proteins are being catabolized, we can calculate a ratio of C per liter of O2 consumed. BMR is influenced by age, gender, physical condition, body weight and genes. 2

3 Three Basic Uses of Nutrients Absorbed by the Digestive System 1. Energy for immediate use by cells to conduct their normal metabolic processes (muscle contraction, secretions, active transport) 2. Synthesize structural or functional molecules to repair and replace cells. (Mitosis and Cytokinesis) 3. Storage as glycogen or fat for later use as energy (nutrient reserves) ALL Living Things from Bacteria to Humans Conduct METABOLISM Metabolism is the ability to acquire and use energy from the environment. Metabolic processes are all the chemical reactions that occur in cells, tissues, organs, and organ systems. Two Kinds of Metabolic Reactions: 1. Catabolism = breakdown of large molecules into simple ones to produce energy. (release energy) 2. Anabolism = build large molecules from simple molecules. (requires energy input) 3

4 Two Basic Kinds of Chemical Reactions found in Biological System Metabolic Turnover and Cellular ATP Production 4

5 Carbohydrate Metabolism Amino acid synthesis: Convert pyruvic acid into an Amino Acid requires a transamination Transamination: Pyruvic Acid + NH3 Glycogenesis: glucose Lipogenesis: glucose Glycogenolysis: glycogen glycogen triglyceride glucose Gluconeogenesis: lactic acid, amino acids, or triglycerides glucose Amino Acid Summary of Glucose Metabolism 5

6 Summary of Gluconeogenesis ATP production from Carbohydrates Glycolysis Substrates required: Glucose, 2 ATP, 4 ADP, and 2 NAD+ Intermediate Reactants: Glucose-6-phosphate, Fructose-1,6 bisphosphate Products: 2 molecules of Pyruvic Acid 2 ATP 2 NADH 6

7 Overview of Cellular Respiration ATP production from Carbohydrates Formation of Acetyl-CoA Substrates required: Products: 2 Pyruvic Acid 2 NAD+ 2 Coenzyme A 2 Acetyl-CoA 2 NADH 2 CO2 7

8 Overview of Cellular Respiration ATP production from Carbohydrates Kreb s cycle Substrates required: 2 Oxaloacetic Acid 2 Acetyl-CoA 6 NAD+ 2 FAD 2 GDP Intermediate Reactants: Citric Acid 8

9 ATP production from Carbohydrates Kreb s cycle Products: 2 Oxaloacetic Acid 6 NADH 2 FADH2 2 GTP 4 CO2 Overview of the Kreb s Cycle 9

10 ATP production from Carbohydrates Electron Transport Chain A series of Oxidative Phosphorylation reactions Oxidation = the removal of electrons from a molecule and results in a decrease in the energy content of the molecule. Because most biological reactions involve the loss of hydrogen atoms, they are called dehydrogenation reactions. Reduction = the opposite of oxidation; the addition of electrons to a molecule, and results in an increase in the energy content of the molecule. Overview of Cellular Respiration 10

11 ATP production from Carbohydrates Electron Transport Chain Substrates required: 10 NADH 2 FADH 6 O2 Products: 32 ATP 6 H20 Overview of Electron Transport System 11

12 Summary of ATP Production Protein Metabolism Deamination: removal of the amino group (NH2) leaving an acetyl molecule Transamination: Adding an amino group to pyruvic acid to produce any of the nonessential amino acids Protein Synthesis: Production of protein molecule using an RNA model. Protein catabolism: breaking down a protein into individual amino acids. 12

13 Lipid Metabolism Lipoproteins: surrounding triglycerides with apoproteins to make them more transportable in water Very low-density lipoproteins (VLDL s) Low-density lipoproteins (LDL s) High-density lipoproteins (HDL s) Lipolysis: break down lipids Beta Oxidation: breaking a fatty acid into 2-carbon compounds Lipogenesis: formation of lipids from nonlipids Overview of the Role of the Liver in Lipid Metabolism 13

14 Summary of the Interconnection Between Tissues and Metabolic Reactions Metabolic Overview: The Absorptive State 14

15 Metabolic overview: The Post-Absorptive State 15